The effects of trovafloxacin in arresting and/or preventing Chlamydia pneumoniae infection of the respiratory tract tissues are being investigated in an in vitro model, using nonhuman primate tracheal epithelial tissues. Using this model, we are working to determine the MIC 90 of trovafloxacin against respiratory infection with C. pneumoniae. Epithelial cells are rinsed, collected and cultured from trachea specimens obtained at necropsy. After reaching near confluent monolayers in culture wells, the cells are infected with C. pneumoniae and monitored for up to seven days. When immature chlamydial inclusions are identified under 40( power, cells are treated with trovafloxacin, and paired with untreated, infected control cultures. Treatment continues for seven days, with nutritive media changes every two days. On the eighth day after initiation of treatment, treated and untreated control culture wells are divided in half. One half are fixed in methanol while the other half are passed onto HL cells for viability assessment. Two days after cell passage, HL cells are fixed and screened for infectivity rates. Results of these studies are pending. FUNDING NIH grant RR00166 and a grant from the Pfizer Pharmaceuticals Group.